express-http-proxy

Express proxy middleware to forward request to another host and pass response back

Install

$ npm install express-http-proxy --save

Usage

proxy(host, options);

To proxy URLS starting with '/proxy' to the host 'www.google.com':

var proxy = require('express-http-proxy');

var app = require('express')();

app.use('/proxy', proxy('www.google.com'));

Options

forwardPath

The forwardPath option allows you to modify the path prior to proxying the request.

var proxy = require('express-http-proxy');

var app = require('express')();

app.use('/proxy', proxy('www.google.com', {
  forwardPath: function(req, res) {
    return require('url').parse(req.url).path;
  }
}));

forwardPathAsync

The forwardPathAsync options allows you to modify the path asyncronously prior to proxying the request, using Promises.

app.use(proxy('httpbin.org', {
  forwardPathAsync: function() {
    return new Promise(function(resolve, reject) {
      // ...
      // eventually
      resolve( /* your resolved eorwardPath as string */ )
    });
  }
}));

filter

The filter option can be used to limit what requests are proxied. For example, if you only want to proxy get request

app.use('/proxy', proxy('www.google.com', {
  filter: function(req, res) {
     return req.method == 'GET';
  },
  forwardPath: function(req, res) {
    return require('url').parse(req.url).path;
  }
}));

intercept

You can intercept the response before sending it back to the client.

app.use('/proxy', proxy('www.google.com', {
  intercept: function(rsp, data, req, res, callback) {
    // rsp - original response from the target
    data = JSON.parse(data.toString('utf8'));
    callback(null, JSON.stringify(data));
  }
}));

decorateRequest

You can change the request options before it is sent to the target.

app.use('/proxy', proxy('www.google.com', {
  decorateRequest: function(reqOpt, req) {
    reqOpt.headers['Content-Type'] = '';
    reqOpt.method = 'GET';
    reqOpt.bodyContent = wrap(req.bodyContent);
    return reqOpt;
  }
}));

preserveHostHdr

You can copy the host HTTP header to the proxied express server using the preserveHostHdr option.

app.use('/proxy', proxy('www.google.com', {
  preserveHostHdr: true
}));

reqAsBuffer

Note: this is an experimental feature. ymmv

The reqAsBuffer option allows you to ensure the req body is encoded as a Node Buffer when sending a proxied request. Any value for this is truthy.

This defaults to to false in order to preserve legacy behavior. Note that the value of reqBodyEnconding is used as the encoding when coercing strings (and stringified JSON) to Buffer.

app.use('/proxy', proxy('www.google.com', {
  reqAsBuffer: true
}));

reqBodyEncoding

Encoding used to decode request body. Defaults to utf-8.

Use null to preserve as Buffer when proxied request body is a Buffer. (e.g image upload) Accept any values supported by raw-body.

The same encoding is used in the intercept method.

app.use('/post', proxy('httpbin.org', {
  reqBodyEncoding: null
}));

timeout

By default, node does not express a timeout on connections. Use timeout option to impose a specific timeout. Timed-out requests will respond with 504 status code and a X-Timeout-Reason header.

app.use('/', proxy('httpbin.org', {
  timeout: 2000  // in milliseconds, two seconds
}));

Questions

Q: Can it support https proxy?

A: Yes, you can use the 'https-proxy-agent' package. Something like this:

var corporateProxyServer = process.env.HTTP_PROXY || process.env.http_proxy || process.env.HTTPS_PROXY || process.env.https_proxy;

if (corporateProxyServer) {
  corporateProxyAgent = new HttpsProxyAgent(corporateProxyServer);
}

Then inside the decorateRequest method, add the agent to the request:

  req.agent = corporateProxyAgent;

Release Notes

Licence

MIT